That was a lot of information, so let's summarize the key ideas.
For the first time, we saw how well-designed hardware can coordinate a complex action on its own and decrease the complexity of the software; we can consider this hardware to be smart. We also expanded our knowledge of mechanisms. We revisited tank treads and used a sturdier construction with more traction that was more suitable for the Omnilander's off-road application. We learned about how worm gears are a convenient way to obtain a mechanical advantage and one-way rotation within a compact footprint. We created our first application for the rack-and-pinion mechanism, a type of linear actuator; we will use rack-and-pinion for a different application later in this book when we build the Falcon race car. Lastly, we saw how a clutch gear can introduce some slip to prevent a gear train from jamming...